Coupled phosphorus-containing amides, precursors thereof and lubricant compositions containing same

ABSTRACT

A load-carrying agent and a lubricating composition containing such an agent is disclosed. The agent is preferably comprised of a statistical mixture of a plurality of different coupled phosphorus-containing amide compounds having the formula ##STR1## wherein X 1 , X 2  and X 3 , independently, is O or S; wherein R 1  and R 2 , independently, is a hydrocarbyl, a hydrocarbyl-based oxy, the hydrocarbyl portion of which contains 6 to 22 carbon atoms, or a hydrocarbyl-based thio having from 4 to about 34 carbon atoms; wherein R 3 , R 4 , R 5  and R 6 , independently, is hydrogen, or an alkyl having from 1 to about 22 carbon atoms, a cycloalkyl having from about 4 to about 22 carbon atoms, or an aromatic, an alkyl-substituted aromatic or an aromatic-substituted alkyl having from 6 to about 34 carbon atoms; wherein n is 0 or 1; wherein n&#39; is 1, 2 or 3; wherein R 7  is hydrogen or an alkyl having from 1 to 22 carbon atoms; and wherein when n&#39; is 1, R 8  is selected from the group consisting of H, --ROH, --ROR, --RSR and ##STR2## and when n&#39; is 2, R 8  is selected from the group consisting of ##STR3## --R-- and --R&#39;-- when n&#39; is 3, R 8  is ##STR4## wherein R is independently hydrogen or an alkyl moiety, alkylene or alkylidene containing 1 to 12 carbon atoms and R&#39; is hydrogen or an alkyl moiety, alkylene, alkylidene or carboxyl containing 1 to 60 carbon atoms.

CROSS-REFERENCES

This application is a continuation-in-part of our pending U.S.application Ser. No. 730,877, filed May 3, 1985, now abandoned, which isincorporated herein in its entirety. We claim priority under 35 USC §120with respect to any and all disclosure made in said earlier filedapplication Ser. No. 730,877.

FIELD OF THE INVENTION

The present invention relates to coupled phosphorus-containing amides,their precursors, lubricant concentrates, and lubricants containing samewhich can be employed in the lubrication of internal combustion engines,hydraulic equipment, and the like. The coupled amides can be prepared,for example, by the reaction of acids such as dialkyl and/or diarylphosphorodithioic acids reacted with unsaturated hydrocarbyl acrylamidesand subsequently coupled by a coupling reaction carried out in thepresence of formaldehyde and/or paraformaldehyde.

BACKGROUND OF THE INVENTION

German Pat. No. 819,998 relates to a method of producing esters ofphosphoric acid or thiophosphoric acid containing a carboxylic acidamide group.

An article by Wolf and Heidenreich, Deutsche Lebensmittel Rundschau,Vol. 64, No. 6, pages 171-177 (1968) relates to the synthesis of organicphosphorus compounds with insecticidal and acaricidal activity such asN,N'-methylenebis(O,O-dialkylphosphorylmercaptoacylamine) wherein thealkyl portion of the dialkyl phosphoryl groups contain 1-4 carbon atomsand the amides may be coupled via a methylene coupler.

U.S. Pat. No. 4,032,461 to Hoke relates to phosphorus andsulfur-containing amides and thioamides as lubricating oil additives andlubricating oil compositions containing the same.

U.S. Pat. No. 4,208,357 to Hoke relates to a process for preparingphosphorus and sulfur-containing amides and thioamides.

U.S. Pat. No. 4,282,171 to Hoke also relates to phosphorus andsulfur-containing amides and thioamides.

SUMMARY OF THE INVENTION

Accordingly, it is an aspect of the present invention to provide coupledphosphorus-containing amide and/or phosphorus-sulfur-containingcompounds (hereinafter referred to as simply phosphorus-containing amidecompounds), the compounds being coupled via an alkylene, ether,thioether, amino, or carboxyl linking groups.

It is a further aspect of the present invention to provide a mixture, ofcoupled phosphorus-containing amide compounds and other functionalderivatives of phosphorus-containing amides in a lubricating compositionwherein the coupling group is represented by one or more of thefollowing structural formula ##STR5## --R-- wherein R is independentlyhydrogen or an alkyl containing 1 to 8 carbon atoms and R' isindependently hydrogen or an alkyl or carboxyl alkyl moiety, alkylene oralkylidene containing 1 to 60 carbon atoms, R is preferably methyl andR' is preferably an alkyl moiety, alkylene or alkylidene containing 1 to28 carbon atoms. Three phosphorus-containing amide compounds can becoupled when the coupler is ##STR6##

It is a further aspect of the present invention to provide an effectiveload-carrying agent in the form of a mixture of such coupledphosphorus-containing amide compounds and their precursors and otherfunctional derivatives of phosphorus-containing amides in minor amountswith other additives in a major amount of a lubricating oil or otherfunctional fluids.

These and other aspects of the present invention will become apparent tothose skilled in the art from the attached specification which fullydescribes the present invention.

A particularly preferred embodiment of the present invention is alubricating composition comprising a major portion of a lubricating oiland a minor portion of a load-carrying agent in the form of a mixture ofcompounds which are encompassed by the general formula ##STR7## whereinX¹, X² and X³, independently, is O or S; wherein R¹ and R²,independently, is a hydrocarbyl, a hydrocarbyl-based oxy, thehydrocarbyl portion of which is an alkyl-containing 6 to 22 carbon atomsor a hydrocarbyl-based thio, having from 4 to about 34 carbon atoms;

wherein R³, R⁴, R⁵ and R⁶, independently, is hydrogen, or an alkylhaving from 1 to about 22 carbon atoms, a cycloalkyl having from about 4to about 22 carbon atoms, or an aromatic, an alkyl-substituted aromaticor an aromatic-substituted alkyl having from 6 to about 34 carbon atoms;

wherein n is 0 or 1;

wherein n' is 1, 2 or 3;

wherein R⁷ is hydrogen or an alkyl having from 1 to 22 carbon atoms; and

wherein when n' is 1, R⁸ is hydrogen, --ROH, --ROR, --RSR, ##STR8## andwhen n' is 2, R⁸ is ##STR9## --R-- when n' is 3, R⁸ is ##STR10## whereinR is independently hydrogen, an alkyl moiety, alkylene or alkylidene of1 to 12 carbons and R' is hydrogen, an alkyl or carboxy alkyl moiety,alkylene or alkylidene containing 1 to 60 carbon atoms, R is preferablymethylene and R' is preferably an alkyl or carboxy alkyl, alkylene,alkylidene containing 1 to 28 carbons.

When n' is 1 or 2, the R' and/or R can be a coupling group as definedabove, hydrogen or an alkyl or carboxy alkyl moiety corresponding to theabove referred to linking group. With respect to when any R⁸ is acoupling group, the R and R' cannot be hydrogen and must be a couplersuch as an alkylene or alkylidene to link together phosphorus-containingamide.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The coupled amide compounds of Formula I (i.e., when n' is 2 or 3) areobtained by the coupling reaction of phosphorus-containing amides. Whilethe uncoupled phosphorus-containing amides are intermediates they arethemselves useful compounds, e.g., load-carrying agents in a lubricantoil and can be reacted to include an R⁸ functional group when n' is 1.Such uncoupled phosphorus-containing amides are likely to be presenttogether with coupled phosphorus-containing compounds of Formula I asused as load-carrying agents in a lubricating oil. Accordingly,load-carrying agents of the present invention may be, and preferablyare, comprised of mixtures of compounds including: (1) a mixture ofdifferent uncoupled phosphorus-containing amides (n' is 1); (2) amixture of coupled phosphorus-containing amides (n' is 2); and (3) amixture of coupled phosphorus-containing amides when n' is 3; whichincludes coupling like and different phosphorus-containing amides viaone or more different coupling agents. In a particularly preferredembodiment, the mixture of Formula I compounds includes compoundswherein n' is 1 and R⁸ is --ROH and coupled compounds wherein n' is 2and R⁸ is ##STR11##

Phosphorus-containing amides will be disclosed and described first,followed by a disclosure and description of coupling agents which inturn will be followed by a description and disclosure of coupled amidecompounds encompassed by generally Formula I.

Phosphorus-Containing Amides

The phosphorus-containing amides which are coupled to make compounds ofFormula I can be made by various alternative routes. A preferred routeinvolves the reaction of (A) an acid having the formula ##STR12## with(B) an acrylamide-type compound having the formula ##STR13## wherein thevarious R and the various X groups are as set forth above. That is, withregard to the acid, X¹ and X² are independently oxygen or sulfur withsulfur being preferred. X³ is also oxygen or sulfur, but oxygen ispreferred. R¹ and R² are independently a hydrocarbyl, ahydrocarbyl-based oxy (preferably, the hydrocarbyl portion containing6-22 carbons), or a hydrocarbyl-based thio with the hydrocarbyl-basedoxy being preferred. Accordingly, the preferred type of (A) compound isa phosphorodithioic acid wherein the hydrocarbyl groups are both alkyl,both aromatic, or one of each as noted hereinabove. Similarly, R³, R⁴and R⁵ are the same as set forth above with hydrogen or methyl beingpreferred. R⁷ can be an alkyl having from 1 to 22 carbon atoms withhydrogen being preferred. The phosphorodithioic acids (Formula A whereinX¹ and X² are sulfur) of the present invention can be made according toany conventional method as well known to the art. Generally, an alcohol,e.g., alkyl alcohol, aromatic alcohol, or both, is reacted with aphosphorus sulfide such as P₂ S₅. A suitable reaction route is set forthin U.S. Pat. No. 3,361,668 hereby fully incorporated by reference forthe purpose of disclosing such a reaction route. Examples of the (B)type reactant include acrylamide, methacrylamide wherein R⁵ is methyl,and crotonamide. The phosphorus-containing amide compounds and coupledcompounds of the present invention are oil-soluble compounds. The needfor oil-solubility is related to the carbon chain length of R¹ -R⁸. Forexample, if R⁸ is methylene, R¹ and R² would contain 6 to 22 carbonatoms to provide oil-solubility.

The reaction between the (A) acid and the (B) amide compound isexothermic and hence only slight heat need be applied thereto. Thereaction conveniently can be carried out in an inert atmosphere such asnitrogen as from about 25° C. to about 100° C. with from about 70° C. toabout 90° C. being preferred. The reaction can be carried out in thepresence or absence of a menstruum. Desirably, the reaction takes placein a solvent medium which typically is a hydrocarbon menstruum such astoluene, xylene, hexane, heptane, kerosene, fuel oil, an oil of alubricating viscosity, and the like or a chlorohydrocarbon such aschoroform, carbon tetrachloride, and the like, or an alcohol such asmethanol, ethanol, propanol, butanol, 2-ethylhexanol, and the like. Themenstruum, in addition to acting as such, imparts favorable processingcharacteristics such as controlling the exothermic reaction as well aspreventing unwanted side reactions. The reaction time, while dependentupon temperature, is usually as short as one or two hours or less.

The reaction of an acid according to Formula A with an acrylamide-typecompound of Formula B yields a compound having the following formula##STR14## Formula of reaction product of (A) and (B).

At this point the R⁸ of Formula I is hydrogen and n' is 1. This reactionproduct is an intermediate. However, it also can serve as an end productfor use as an additive in a lubricating composition where it functionsas a load-carrying agent, an extreme pressure anti-wear agent, acorrosion-inhibitor, and the like.

The intermediate reaction product of (A) and (B) can be coupled in amanner such as described below and/or further reacted in various waysknown to those skilled in the art to include other functional groups R⁸on the nitrogen atom which groups include --ROH, --ROR, --RSR, ##STR15##wherein R and R' are as defined above.

An alternative, although somewhat less desired, method of preparingphosphorus-containing amides relates to reacting an (A) acid having theformula ##STR16## with (D) a compound having the formula ##STR17##

Dependent on what other substituents are, R¹ and R² may need to containa larger number of carbon atoms in order to provide oil-solubility.

The (A) acid is the same as set forth above with regard to the precedingreaction product and hence X¹ and X² can be oxygen or sulfur with sulfurbeing preferred. While X³ can also be oxygen or sulfur, oxygen ispreferred. Similarly, R¹ and R² are the same as set forth above andhence will not be repeated. As previously noted, R¹ and R² can both bean alkyl having from 1 to 25, preferably 4 to 25 carbon atoms or canboth be an alkyl-substituted aromatic wherein the alkyl substituent hasfrom 1 to 28 carbon atoms. Moreover, one of the R¹ and R² groups can bean alkyl with the remaining group being an alkyl-substituted aromatic.Additionally, more than one acid having the above (A) formulation can beutilized having R¹ and R² substituents therein as set forth in theimmediately preceding sentence thereby ensuring that a statisticalmixture of the various alkyl and the various alkyl-substituted aromaticgroups will exist.

Considering the (D) component, it is somewhat similar to compoundFormula (B) set forth hereinabove except that it is coupled by an R⁸group. Accordingly, the definition of R³, R⁴, R⁵ and R⁷ is the same asset forth hereinabove with regard to compound (B) and hence will not berepeated but rather is fully hereby incorporated by reference. Thus, byway of summary, the various R³, R⁴, R⁵ and R⁷ groups are essentiallysaturated hydrocarbyls and preferably are either methyl or hydrogen.Considering R⁸ is the same as discussed above with regard to Formula I.R⁸ is preferably ##STR18##

As with the reaction between acid (A) and compound (B), the reactionbetween acid (A) and compound (D) is also exothermic and thus requiresonly a slight amount of heat. Essentially the reaction of compound (D)with the (A) acid is very similar to the reaction of compound (B) andacid (A). Accordingly, the present reaction is carried out desirably inan inert atmosphere at a temperature from about 25° C. to about 100° C.with from about 70° C. to about 90° C. being preferred. The reactiontime is generally short, for example on the order of less than an houror two. Once again, hydrocarbon solvents such as toluene, xylene,hexane, heptane, kerosene, fuel oil, an oil of a lubricating viscosity,and the like or chlorinated hydrocarbon such as chloroform, carbontetrachloride, and the like, or an alcohol such as methanol, ethanol,propanol, butanol, 2-ethylhexanol, and the like, are utilized. Once theproduct has been formed, the various solvents can be removed bystripping under a vacuum and the like.

Yet another alternative method of preparing compounds according to thepresent invention and especially the coupled compounds set forthhereinabove containing an R⁶ group is via a displacement reaction. Inthis reaction, a metal salt of the (A) acid, that is a metal saltaccording to Formula E ##STR19## is reacted with a compound of Formula F##STR20##

X¹, X², X³, R¹, R², R³, R⁴, R⁵, R⁶, R⁷ and n are the same as set forthabove and accordingly the description thereof is hereby fullyincorporated. M is an alkali metal such as sodium, potassium or thelike, or an alkaline earth metal such as manganese, calcium or the like,or hydrogen, with sodium and potassium being preferred. Considering X⁴,it is a displaceable halogen or carbon group well known to the art suchas Cl, Br, I, tosyl, mesyl, and the like. The reaction between thecompounds of Formulae E and F proceeds in a manner very similar to thatset forth above with regard to making the reaction product betweencompound A and compound B. Accordingly, the description with regardthereto will not be repeated. Briefly, the reaction is carried out at atemperature of about 10° C. to about 200° C. with from about 50° C. toabout 150° C. being preferred. Naturally an inert atmosphere such asnitrogen is utilized. Although not required, the reaction can take placein a menstruum. The solvent also renders by-product salts, e.g., KCl,NaCl, NaBr, KBr, etc., which are insoluble in the reaction medium andeasily removed by filtration. The amount of Formulae E and F compoundsare generally an equivalent amount. The formed product has the followingformula ##STR21##

Coupling Agents

After the reaction product of (A) and (B) is formed, these reactionproducts are preferably coupled by reacting them with a (C) aldehyde orketone (or a reaction synthon equivalent of an aldehyde or ketone) ofthe following formula ##STR22## R⁹ and R¹⁰ independently can behydrogen, an alkyl having from 1 to 12 carbon atoms, phenyl, or analkyl-substituted phenyl having from 7 to 12 carbon atoms. Desirablycompound (C) is an aldehyde, i.e., R¹⁰ is H, having a total of 1 to 3carbon atoms therein with one carbon atom, that is formaldehyde andparaformaldehyde being highly preferred which can result in methyleneand di-methylene ether coupling groups.

The coupling reaction desirably takes place in the presence of strongmineral or organic acids such as HCl, H₂ SO₄, H₃ PO₄, CH₃ SO₃ H,p-toluenesulfonic acid, and the like. The amount of the acid catalyst isgenerally from about 0.3 to about 1.5% by weight, desirably from about0.8 to about 1.2%, and preferably from about 0.9 to about 1.1% by weightbased upon the weight of the total product formed. Although lesseramounts of catalyst can be utilized, the reaction is generally slowerand a smaller fraction of the desired product is formed. The reactionwith Formula C initially takes place at a temperature of from about 80°C. to about 120° C. and desirably from about 80° C. to about 100° C. inan inert atmosphere. The final reaction temperature is generally higheras from about 100° C. to about 150° C. and desirably from about 125° C.to about 135° C.

Alternatively, if one wishes to stop at the carbinol stage, (Formula IIwhere X=O) the reaction between A and B is best carried out using basiccatalysts, i.e., NaHCO₃, KHCO₃, KHCO₃, Na₂ CO₃, KCO₃, NaOH, KOH, etc.This reaction mixture can be neutralized with acid and heated to removewater; reacted with H₂ S, NaHS or Na₂ S or other source of S⁻² ; or, NH₃or R"NH₂ where R" is alternatively H, alkyl of 1-60 carbon atoms, aryl,alkyl substituents, aryl or aryl substituted alkyl of 6-30 carbon atomsor acyl of 1-22 carbon atoms to form the ether (Formula I, X=O), thio(Formula I, X=S) or amino (Formula I, X=N).

The amount of reactants (A) and (B) desirably is a 1:1 equivalent weightratio although greater or lesser amounts can be utilized. A 1:1equivalent weight ratio of the two reactants is desirable in thatotherwise a higher acid number is obtained than desired or else one ofthe reactants is literally wasted. The amount of reaction product formedand reacted with coupling agent (C) is from about 0.3 to about 3.0weight equivalents utilized per weight equivalent of said (C) aldehydeor ketone compound with a 1:1 equivalent ratio being preferred. Thecoupler (C) may be a mixture of different couplers and preferblyincludes paraformaldehyde.

The combination of formaldehyde and phosphorus containing amide compoundas described above may couple two amides or may result in the formationof a --CH₂ OH on the nitrogen atom of the amide. Two of such amides witha --CH₂ OH group thereon may then be reacted to form a coupled amidewith the coupling group being ##STR23## Such a coupling reaction maytake place during use of such uncoupled compounds which reaction isendothermic. The endothermic reaction may be beneficial to theload-carrying lubricating properties of the overall oil composition.

Other couplers (R⁸ in Formula I when n' is 2 or 3) and functional groups(R⁸ in Formula I when n' is 1) can be attached to the nitrogen atoms ofthe phosphorus containing amides described above by procedures known tothose skilled in the art.

As briefly discussed above, the compounds of the present invention areparticularly useful as additives for lubricating compositions. Thecompounds of the present invention are particularly useful as additivesfor lubrication where they function primarily as load-carrying agents,high or extreme pressure anti-wear agents, oxidation inhibitors,corrosion-inhibitors, and the like. Lubricating compositions containingthe compounds of the present invention as additives comprise a majorproportion of a lubricating oil and a minor portion of said compoundsufficient to improve the load-carrying ability, anti-wear ability,oxidation-inhibitor or corrosion-inhibiting properties of thecomposition. In general, the compounds are used in lubricants in anamount of from about 0.01 to about 5% by weight and desirably from about0.1 to about 1% by weight based upon the total weight of the lubricatingcomposition. Additionally, the compounds of the present invention can beutilized in a concentration form or a lubricant concentrate in an amountof from about 0.5 to about 50% by weight and more desirably from about 1to about 25% by weight based upon the total weight of the concentratepackage. In addition to the compounds of the present invention, theconcentrate package can contain one or more compounds such as anti-wearagents, load-carrying agents, corrosion-inhibitors, oxidationinhibitors, demulsifiers, foam inhibitors, VI improvers, pour pointdepressants, detergents, dispersants, and the like. The compounds of thepresent invention can also be used as insecticides or pesticides.

Coupled Amides

According to the present invention, various couplers are used to providea variety of different types of coupled phosphorus-containing amides.Other reactions attach other functional groups to thephosphorus-containing amides. These uncoupled compounds may be presentin a mixture with the paraformaldehyde coupled amides in a lubricant oilwhich is useful in providing the desirable properties or load-carryingagents, extreme pressure agents, and generally as additives inlubricating compositions.

A preferred form of the present invention is a statistical mixture ofcompounds having the following formula ##STR24##

Considering X¹ and X², it independently is oxygen or sulfur andpreferably is sulfur whereas X³ is O or S and preferably O. R¹ and R²each independently is a hydrocarbyl, a hydrocarbyl-based thio orpreferably a hydrocarbyl-based oxy group wherein the hydrocarbyl portioncontains 6 to 22 carbon atoms. The hydrocarbyl portion of R¹ and R²generally contains from 1 to about 34 carbon atoms. When R⁷ is hydrogenand R⁸ is methylene, R¹ and R² will contain 6 to 12 carbon atoms inorder to provide for sufficient oil-solubility for the compound (I). Thehydrocarbyl portion of R¹ and R² independently can be alkyl or aromatic.Although the hydrocarbyl portion of both R¹ and R² can be the same typeof hydrocarbyl group, that is both alkyl or both aromatic, often onesuch group can be alkyl and the remaining group can be aromatic.Different Formula I compounds which are made by reacting a mixture oftwo or more different reactants each containing an alkyl hydrocarbylgroup as well as an aromatic hydrocarbyl (R¹ and R²) group therein. Thesame or different compounds are coupled via different coupling groups R⁸to form a statistical mixture of coupled compounds or are reacted withdifferent compounds to provide different functional groups R⁸ thereon.

The term "hydrocarbyl substituent" or "hydrocarbyl group" is meantthroughout this entire specification as well as the claims herein todenote a group having a carbon atom directly attached to the remainderof the molecule and having predominantly hydrocarbon character withinthe context of this invention.

The hydrocarbyl group of R¹ or R² is preferably an alkyl containing from6 to 22 (more preferably 8-12) carbon atoms. Examples of such groupsinclude hexyl, heptyl, octyl, nonyl, decyl, dodecyl, tetradecyl,octadecyl, behenyl, and the like, including all isomers thereof. Shouldthe R¹ or R² hydrocarbyl be an aromatic, it can be phenyl or naphthyl.Oftentime it will have an alkyl substituent thereon. Thus, thealkyl-substituted aromatic can have an alkyl substituent containing from0, that is phenyl, to about 28 carbon atoms, and preferably from about 7to about 12 carbon atoms. Whenever a blend of the compounds of Formula Iis utilized containing significant or effective amounts of alkyl type R¹or R² substituents, the aromatic substituent can contain preferably fromabout 6 to about 12 carbon atoms in the alkyl group thereof, that is,the alkyl-substituted aromatic. This is because although the solubilityof phenyl or low alkyl-substituted aromatics may be somewhat low, theoverall solubility in a lubricant composition is generally increased toa desirable level through the utilization of the R¹ and R² hydrocarbylportions which are alkyl and/or through the use of R⁷ and/or R⁸ groupswhich have a large number of carbon atoms therein. The use of loweralkyls, e.g., less than 6 carbon atoms at R¹ and R² above with amethylene at R⁸ is undesirable with respect to oil solubility.

Considering now the alkyl-substituted aromatic group, the aromaticpreferably is phenyl while the alkyl can be the same as set forthhereinabove. Specific examples of such alkyl groups on the aromaticnucleus include methyl, ethyl, propyl, butyl, pentyl, heptyl, octyl,decyl, behenyl, and the like including isomers thereof.

Accordingly, specific examples of mixed hydrocarbyl (R¹ and R²) portionsor substituents include tolyl and octyl, tolyl and hexyl, isobutylphenyland amyl, phenyl and isooctyl, and the like. Mixed hydrocarbyl (R¹ andR²) substituents are also assured when cresylic acids are utilized toform the phosphorus portion of the Formula I compound. The sources, typeand variety of cresylic acids are known to those skilled in the art. Thenumber of different molecular entities in the mixture is furtherincreased by the different coupling groups, R⁸ as defined above forFormula I when n' is 2 or 3.

When X¹ and X² is sulfur and especially when X² is sulfur, the alkylhydrocarbyl substituent (R¹ or R²) contains 6 or more carbon atoms.However, when X¹ or X² is oxygen and especially when X² is oxygen, thealkyl hydrocarbyl substituent (R¹ or R²) is 6 to 12 carbon atoms.

Considering R³, R⁴, R⁵ and R⁶, each independently can be hydrogen or asaturated hydrocarbyl having up to 22 carbon atoms. The saturatedhydrocarbyl group can be an alkyl having from 1 to 22 carbon atoms, acycloalkyl having from 4 to 22 carbon atoms, or an aromatic, anaromatic-substituted alkyl or an alkyl-substituted aromatic having from6 to about 34 carbon atoms. Preferably, R³, R⁴, R⁵ and R⁶ is hydrogen ormethyl with hydrogen being highly preferred. Examples of specific R³,R⁴, R⁵ and R⁶ alkyl groups include methyl, ethyl, propyl, butyl, pentyl,hexyl, heptyl, octyl, nonyl, decyl, dodecyl, tetradecyl, etc., as wellas isomers thereof whereas examples of specific aromatic groups includephenyl, tolyl, naphthyl, heptylphenyl, nonylphenyl, dodecylphenyl,wax-substituted phenyl, and the like. With regard to the R⁵ --C--R⁶group, n can be 0 or 1. Preferably n is 1.

Considering now the amide portion of the molecule, R⁷ is hydrogen or analkyl having from 1 to 22 carbon atoms with hydrogen being highlypreferred. Examples of specific alkyl groups include methyl, ethyl,propyl, butyl, and so forth including the various isomers thereof.

A particularly preferred embodiment of the invention includes astatistical mixture (i.e., coupled and uncoupled compounds each withdifferent substituent groups providing a variety of different compounds)of different phosphorus containing amide compounds bonded to or coupledby different R⁸ groups with the proviso that in general Formula I themixture includes some compounds wherein n' is 1 and R⁸ is --CH₂ OH andalso where n' is 2, R⁸ is ##STR25## Any such statistical mixture islikely to include some coupled amide compounds of Formula I wherein R⁸is methylene. When R⁸ is methylene, R¹ and R² generally must containmore than 6 carbon atoms in order to maintain good oil solubility. Whenn' is 1, R⁸ is selected from the group consisting of H, --ROH, --ROR,--RSR and RN(R)₂ and when n' is 2 or 3, R⁸ is selected from the groupconsisting of ##STR26## --R-- and --R'-- and when n' is 3, R⁸ is##STR27## wherein R is independently hydrogen or an alkyl moiety,alkylene or alkylidene of 1 to 12 carbon atoms and R' is hydrogen or analkyl or carboxy alkyl moiety, alkylene or alkylidene of containing 1 to60 carbon atoms, R is preferably methylene and R' is preferably an alkylmoiety of 1 to 28 carbons. When R and R' are linking groups, they may bealkylene and/or alkylidene, i.e., the linkage may be vicinal and/orgeminal. Compounds of Formula I are believed to be novel compounds andthose which are oil-soluble are of particular interest to the presentinvention.

The following illustrate the preparation of compounds of the presentinvention. All parts and percentages are by weight unless otherwiseindicated.

EXAMPLE 1

To a mixture of 1775 parts (4.26 equivalents) of O,O-di-isooctylphosphorodithioic acid and 980 parts of toluene under a nitrogenatmosphere are added 302 parts (4.26 equivalents) of acrylamide. Thereaction mixture exotherms to about 56° C. and 77 parts (2.33equivalents) of paraformaldehyde and 215 parts (0.11 equivalent) ofp-toluenesulfonic acid hydrate are added. Heating is continued at reflux(92°-127° C.) while removing 48 parts of water. Upon cooling the mixtureto 100° C., 9.2 parts (0.11 equivalent) of sodium bicarbonate is addedand cooling continued to about 30° C. A vacuum is applied (15 mm. Hg)and toluene solvent removed while raising the temperature to 110° C. Theresidue is filtered through a filter aid and the filtrate is the desiredproduct. The product contains 6.86% P (6.74% theory).

EXAMPLE 2

To a mixture of 1494 parts (3.79 equivalents) of O,O-di-isooctylphosphorodithioic acid and 800 parts of toluene under a nitrogenatmosphere are added 537 parts (3.79 equivalents) of 50% aqueousacrylamide solution over a period of one hour. The reaction mixtureexotherms to about 53° C. and 64 parts (1.93 equivalents) ofparaformaldehyde and 18 parts (0.095 equivalent) of p-toluenesulfonicacid hydrate are added. Heating is continued at reflux (91°-126° C.) for4 hours while collecting 305 parts of water. The mixture is cooled toabout 90° C. and 7.6 parts (0.095 equivalent) of 50% aqueous sodiumhydroxide solution are added. Cooling is continued to about 30° C. and avacuum is applied (15 mm. Hg). Toluene solvent is removed while raisingthe temperature to 110° C. The residue is filtered through a filter aidand the filtrate is the desired product. The product contains 6.90% P(6.75% theory) and 2.92% N (2.97% theory).

EXAMPLE 3

To a mixture of 984 parts (1.30 equivalents) of O,O-p-di-dodecylphenylphosphorodithioic acid and 575 parts of toluene under a nitrogenatmosphere are added 100 parts (0.65 equivalent) ofmethylenebisacrylamide. The reaction mixture exotherms to about 40° C.and is heated at 80°-85° C. for 2 hours. After cooling the mixture to30° C., a vacuum (15 mm. Hg) is applied and toluene solvent is removedwhile raising the temperature to 100° C. The residue is filtered througha filter aid and the filtrate is the desired product. The productcontains 4.09% P (4.31% theory).

EXAMPLE 4

A reaction vessel is charged with 820 parts of toluene and 930 parts(2.32 equivalents) of a O,O-dialkyl phosphorodithioic acid prepared froma mixture of 20 mole percent isobutyl alcohol and 80 mole percent2-ethylhexyl alcohol. To this mixture under a nitrogen atmosphere areadded 178.6 parts (1.16 equivalents) of methylenebisacrylamide. Themixture exotherms to about 65° C. and is heated at about 80°-85° C. for2 hours. Upon cooling to 50° C., a vacuum (30 mm. Hg) is applied.Toluene solvent is removed while raising the temperature to 115° C. Theresidue is filtered through a filter aid and the filtrate is the desiredproduct. The product contains 7.30% P (7.28% theory).

EXAMPLE 5

To a mixture of 305 parts of toluene and 611 parts (1.82 equivalents) ofa O,O-di-alkyl-substituted phosphorodithioic acid prepared from amixture of 20 mole percent phenol and 80 mole percent i-octyl alcohol,are added 258 parts (1.82 equivalents) of a 50% aqueous acrylamidesolution over a 20-minute period under a nitrogen atmosphere. After aninitial exotherm to 60° C., 32.1 parts (0.97 equivalent) ofparaformaldehyde and 7.3 parts (0.038 equivalent) of p-toluenesulfonicacid hydrate are added. The mixture is heated at reflux (91°-127° C.)for 2 hours while removing 131 parts of water. The mixture is cooled to80° C. and 3.1 parts (0.038 equivalent) of 50% aqueous sodium hydroxidesolution is added. Cooling is continued to 50° C. and a vacuum (30 mm.Hg) is applied. Toluene solvent is removed while raising the temperatureto 110° C. The residue is filtered through a filter aid and the filtrateis the desired product. The product contains 7.09% P (7.42% theory).

EXAMPLE 6

To 1017 parts (3.0 equivalents) of O,O-di-4-methyl-2-pentylphosphorodithioic acid under nitrogen is added 213 parts (3.0equivalents) of acrylamide. The reaction exotherms to 65° C. and heldfor one to three hours at 65°-75° C. The product is filtered through afilter aid and the filtrate is the desired product. The product contains7.65% P (7.82% theory), 3.51% N (3.50% theory), and 16.05% S (16.06%theory).

EXAMPLE 7

To 614 parts (1.5 equivalents) of O,O-di-isooctyl phosphorodithioic acidunder nitrogen is added 213 parts (1.5 equivalents) of a 50% aqueousacrylamide solution. The reaction exotherms to 65° C. and held for twohours at 70° C. A vacuum is applied (20 mm. Hg) while raisingtemperature to 90° C. The residue is filtered through a filter aid andthe filtrate is the desired product. The product contains 6.67% P (6.60%theory), 2.94% N (2.97% theory), and 14.50% S (13.60% theory).

EXAMPLE 8

To 1340 parts (3.41 equivalents) of O,O-di-isooctyl phosphorodithioicacid under nitrogen is added 242 parts (3.41 equivalents) of acrylamide.The reaction exotherms to 60° C. and is held at 65°-70° C. for one hour.To this mixture are added 400 parts of toluene, 14 parts of potassiumcarbonate, and 307 parts (3.58 equivalents) of 35% aqueous formaldehyde.The mixture is heated under a nitrogen atmosphere at 35°-40° C. for 16hours. To this mixture is added 18.2 parts of glacial acetic acid.

EXAMPLE 9

From the product of Example 8, water is removed using a Dean Stark trapat reflux for 6 hours. After 234 parts of water is collected(temperature is 120° C.), the mixture is cooled to 30° C. A vacuum isapplied (30 mm. Hg) while raising temperature to 115° C. The mixture isfiltered through a filter aid and the filtrate is the desired product.The product contains 6.71% phosphorus.

As previously noted, the compositions of the present invention areuseful as additives for lubricants and functional fluids. They can beemployed in a variety of lubricants based on diverse oils of lubricatingviscosity, including natural and synthetic lubricating oils and mixturesthereof.

These lubricating compositions containing the subject additiveconcentrates are effective as crankcase lubricating oils forspark-ignited and compression-ignited internal combustion engines,including automobile and truck engines, two-cycle engines, aviationpiston engines, marine, railroad and low-low diesel engines, and thelike. Also, automatic transmission fluids, transaxle lubricants, gearlubricants, metal-working lubricants, hydraulic fluids, and otherlubricating oil and grease compositions can benefit from theincorporation of the subject additive concentrates.

As noted above, the coupled phosphorus-containing amide type compoundsof the present invention can be added directly to the lubricant inamounts as set forth above. Additionally, they are often diluted with asubstantially inert, normally liquid organic diluent such as mineraloil, naphtha, benzene, toluene, xylene, and the like to form an additiveconcentrate. The concentrates can furthermore contain one or moreadditives known to the art or described hereinabove. The remainder ofthe concentrate is a substantially inert normally liquid diluent.

An example of a concentrate is as follows:

    ______________________________________                                        Product of Example 2   15% by wt.                                             Zn salt of a phosphoro-                                                                              50% by wt.                                             dithioic acid                                                                 Oxidation inhibitor    20% by wt.                                             Rust inhibitor          5% by wt.                                             Mineral oil            10% by wt.                                             ______________________________________                                    

The concentrate had good solubility with regard to the product ofExample 2 therein.

When one part by weight of the above concentrate was used in 99 parts byweight of a mineral oil and the resulting solution tested with regard toa F.Z.G. gear test, an improvement from a pass 10 load stage to a pass12 load stage was noted.

While in accordance with the patent statutes, a best mode and preferredembodiment has been set forth, it is to be understood that variousmodifications thereof will become apparent to those skilled in the artupon a reading of the specification. Therefore, it is to be understoodthat the invention disclosed herein is intended to cover suchmodifications as fall within the scope of the attached claims.

We claim:
 1. A coupled phosphorus-containing amide compound having theformula ##STR28## wherein X¹, X² and X³, independently, is O or S;wherein R¹ and R², independently, is a hydrocarbyl, a hydrocarbyl-basedoxy, the hydrocarbyl portion of which contains 6 to 22 carbon atoms, ora hydrocarbyl-based thio, having from 4 to about 34 carbon atoms;whereinR³, R⁴, R⁵ and R⁶, independently, is hydrogen, or an alkyl having from 1to about 22 carbon atoms, a cycloalkyl having from about 4 to about 22carbon atoms, or an aromatic, an alkyl-substituted aromatic or anaromatic-substituted alkyl having from 6 to about 34 carbonatoms;wherein n is 0 or 1; wherein n' is 2, or 3; wherein R⁷ is hydrogenor an alkyl having from 1 to 22 carbon atoms; and when n' is 2, R⁸ isselected from the group consisting of ##STR29## --R-- and --R'-- whereinR is independently an alkyl moiety, in the form of alkylene oralkylidene containing 1 to 12 carbon atoms and R' is an alkyl moiety,alkylene, alkylidene or carboxyl containing 1 to 60 carbon atoms andwhen n' is 3 R⁸ is ##STR30##
 2. The coupled phosphorus-containing amidecompound as claimed in claim 1 wherein n' is 2 and R⁸ is a ##STR31##coupling group.
 3. The coupled phosphorus-containing amide compound asclaimed in claim 1 wherein the hydrocarbyl portion of R¹ and R²,independently, is an alkyl having from 6 to 12carbon atoms or analkyl-substituted aromatic wherein said alkyl substituent has from 1 to12 carbon atoms; wherein R³, R⁴, R⁵ and R⁶, independently, is hydrogenor methyl; wherein n is 1: and `wherein X¹ and X² is S, and wherein X³is O.
 4. The coupled phosphorus-containing amide compound as claimed inclaim 1 wherein R¹ and R² is octyloxy and where n' is 2 R⁸ is ##STR32##5. A lubricating composition comprising an oil of lubricating viscosityand a load-carrying agent therein, the agent comprising a statisticalmixture of a plurality of different coupled phosphorus-containing amidecompounds having the formula ##STR33## wherein X¹, X² and X³,independently, is O or S; wherein R¹ and R², independently, is ahydrocarbyl, a hydrocarbyl-based oxy, the hydrocarbyl portion of whichcontains 6 to 12 carbon atoms, or a hydrocarbyl-based thio, having from4 to about 34 carbon atoms;wherein R³, R⁴, R⁵ and R⁶, independently, ishydrogen, or an alkyl having from 1 to about 22 carbon atoms, acycloalkyl having from about 4 to about 22 carbon atoms, or an aromatic,an alkyl-substituted aromatic or an aromatic-substituted alkyl havingfrom 6 to about 34 carbon atoms; wherein n is 0 or 1; wherein n' is 2;wherein R⁷ is hydrogen or an alkyl having from 1 to 22 carbon atoms; andR⁸ is ##STR34## wherein R is an alkyl moiety, alkylene or alkylidenecontaining 1 to 12 carbon atoms.
 6. The lubricant composition as claimedin claim 5 wherein the hydrocarbyl portion of R¹ and R², independently,is an alkyl having from 6 to 12 carbon atoms or an alkyl-substitutedaromatic wherein said alkyl substituent has from 1 to 12 carbonatoms;wherein R³, R⁴, R⁵ and R⁶, independently, is hydrogen or methyl;wherein n is 1; wherein R⁷ is hydrogen; and wherein X¹ and X² is S, andwherein X³ is O.
 7. The lubricant composition as claimed in claim 5wherein R⁸ is ##STR35##
 8. The lubricant composition as claimed in claim5 wherein the composition is a concentrate containing from about 1% toabout 50% by weight of the load-carrying agent.
 9. The lubricatingcomposition as claimed in claim 5 wherein the load-carrying agent ispresent in an amount in the range of from about 0.0001 parts by weightto about 2.0 parts by weight.
 10. The lubricating composition as claimedin claim 9, wherein the load-carrying agent is present in an amount inthe range of from about 0.001 parts by weight to about 0.5 parts byweight.